The invention relates to an electrical circuit breaker with self-extinguishing expansion comprising one or more poles housed in a sealed enclosure filled with an insulating gas with a high dielectric strength, notably sulphur hexafluoride, each pole having an arc extinguishing chamber housing :
a stationary contact,
a movable contact securedly united to a sliding pin passing tightly through a wall of the extinguishing chamber,
means for rotating an arc which is formed when the contacts separate,
and a gas exhaust channel arranged in at least one of the contacts to provide communication and gas outflow between the extinguishing chamber and the expansion volume of the enclosure when the contacts separate.
The presence of a rotating arc in a self-extinguishing expansion circuit breaker having an extinguishing chamber with a cylindrical revolution surface causes a uniform rotation movement of hot gas around the arcing area between the separated contacts. Depending on the intensity of the current to be broken, this gas movement limits the gas exchanges between the other volumes of the extinguishing chamber, and is liable to decrease the quality of the gas outflow during the extinguishing period.
A rotating gas plug may even partially obstruct the exhaust channel inlet, limiting the gas outflow, which compromises extinguishing of the arc.
The object of the invention consists in improving the breaking performances of a circuit breaker with self-extinguishing expansion and arc rotation.